Get All Vehicles

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already mark the tool read-only and idempotent, and the description adds substantial behavioral context: results are cached for 5 minutes, an empty result explains pairing happens in the Tibber app, and a server_unavailable error means server-side re-authorization rather than a bad request. No contradiction with annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Every sentence earns its place: the main action, the positioning as a discovery step, caching behavior, empty-result behavior, and error semantics are all packed into a compact, well-structured description.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a zero-parameter discovery tool with an output schema, the description is remarkably complete. It covers the key output fields, the caching behavior, the empty-result hint, and error interpretation, leaving no meaningful gap for the agent to guess.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

There are zero parameters, so the baseline is 4. The description cannot add parameter meaning beyond the schema, but it does usefully define how vehicle_id values (VIN or case-insensitive name substring) are represented, which helps the agent use the sibling tools correctly.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource: 'List all vehicles paired to the connected Tibber account' and enumerates the included fields (VIN, name, model). It also clearly distinguishes this tool from its siblings by calling it the 'read-only discovery step' that supplies vehicle_id values to the other two tools.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It explicitly instructs the agent to 'call this first' and explains that the purpose is to learn which vehicle_id values the other tools accept. This gives clear when-to-use guidance and routes the agent into the correct workflow without ambiguity.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.